Short answer·Standard multi-step (3/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
A class chart lists Dobereiner's triads, Newlands' law of octaves and Mendeleev's periodic table. State one useful idea and one limitation from these early classifications.
Total: 3 marks
(a) State one useful idea from any one early classification. (1 mark)
(b) State one limitation from Dobereiner's or Newlands' classification. (1 mark)
(c) State how the modern table corrected the basis of arrangement. (1 mark)
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